This section provides background information related to the present disclosure which is not necessarily prior art. This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
A design strategy for a composite material, and an exemplary embodiment of that design, is presented that optimally and repeatedly dissipates energy transmitted through a composite as a result of an impact event. The design strategy, according to the principles of the present teachings, uses one or more elastic layers to modulate the frequency content of the stress wave traveling through the composite, and a viscoelastic layer to dissipate energy at that frequency. Our current experimental and computational results demonstrate that this design efficiently mitigates the pressure and dissipates the energy transmitted through the composite.
In some embodiments of the present teachings, a composite structure consisting of lightweight elastic and viscoelastic components chosen and configured to optimally reduce the impulse, while simultaneously mitigating the force (pressure) transmitted through the composite material from an impact load, is provided and is generally referred to as the MITIGATIUM™ design. The innovation of the approach that led to the development of this MITIGATIUM™ design rubric is that it recognizes that a highly dissipative material alone is generally not going to be useful in impact loadings. Rather, optimal, repeated dissipation can be obtained only by means of a layered composite in which the dissipative component is matched to the other components based on specific relationships among their respective mechanical properties.
According to the principles of the present teachings, the properties of the elastic and viscoelastic components, and their placement within the layered system, are optimally chosen to achieve three outcomes: 1) attenuate the pressure transmitted through the composite; 2) modulate the frequency content of the stress waves within the composite layers so that 3) the energy imparted by the impulse is efficiently dissipated as it is transmitted through the composite. The synergistic nature of MITIGATIUM™ arises because it couples the dissipative component to other component(s) specifically chosen to tune the stress wave traveling through the elastic materials to a frequency at which it can most efficiently be dissipated by the viscous response of the dissipative layer. Thus the innovation has little to do with the actual materials chosen for this demonstration of MITIGATIUM™, but instead lies with the concept of tuning and with the method to choose the specific combination of material properties required for a given application. In theory there is no limit to the number of combinations of elastic and viscoelastic materials that can satisfy the MITIGATIUM™ design rubric. However, the design would need to be tailored to different applications.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
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